Shelley Mountjoy is involved in the atheist movement on both the national and local level. She is best known, in the Washington DC Metropolitan Area, as the current Organizer of Capital Beltway Atheists although she is a leader in several local groups. Nationally, Shelley serves on the Board of Directors of the Secular Student Alliance and on the Advisory Board of Atheist Nexus.

Shelley uses a wheelchair for mobility due to an injury to her spinal cord. She lives in Central Virginia with a cat and dog.